Malawi has a large potential for renewable energy exploitation in a number of areas, the significant ones being solar energy, biomass, and hydropower with potential for geothermal and wind energy. Except for large scale hydropower, which serves as a major source of electricity, the current state of exploitation and utilization of the renewable energy sources in the country is very low, limited largely to pilot and demonstration projects. This section gives a review on the available energy potential of different renewable energy sources and the current status of exploitation is presented.
Malawi has an estimated gross theoretical potential of 1670 MW and the average power generation of 15 000 GWh/year. The technical and economically feasible hydro capacity has been estimated at 6 000 and 7 000 GWh/year, respectively (Taulo, 2007). Current hydropower generation is about 17% of the nation’s hydropower potential and represents 98% of total installed grid-connected electricity generation capacity. Hydropower potential of Malawi is concentrated on the Shire River. The capacity ranges from 18 to 140 MW. The estimated hydro potential of the Shire River is about 600 MW, equivalent to an annual production of 3500 GWh (ibid). In addition, several smaller rivers such as the Songwe, South Rukuru, Dwangwa and Bua, have limited potential at a number of sites estimated to total about 300-400 MW (WEC, 2002).
In addition, Malawi also has huge untapped small hydropower potential (with capacities of less than 10 MW each) which are spread out across the country. The gross theoretical small hydro potential of the country is 150 MW, out of which only 4.5 MW of the economically feasible potential has been developed (MEM, 1997). The exploitability of these is limited by their projected costs, but they could be useful for off-grid or stand-alone-mini grid electrification.
5.2.2 Solar energy
Solar energy presents considerable potential that can contribute to a large extent to fill the gap of energy needs in Malawi. The country receives about 2138 to 3087 hours of sunshine and 2133 kWh/m2/year. The global solar radiation on a horizontal surface ranges between 4.3 kWh/m2/day minimum and 7 kWh/m2/day maximum. The annual daily mean global solar radiation is about 5.86 kWh/m2/day, equivalent to 250 million tonnes of oil equivalent. Maximum irradiation of 6.5-7.0 kWh/m2/day occurs in September – October and the minimum of 4.3-4.6 kWh/m2/day occurs in January-February or in June-July according to location. Peak hourly solar radiation is more than 1000 kWh/m2 during November to December (Chima, 1998). Considering that many parts of the country receive 8 to 12 hours of sunshine per day of 244 W/m2, the potential for using solar for electricity generation is very high. The total available solar energy potential over the total geographical area (i.e. 94,280 km2), of Malawi is calculated to be 356,284,837 MWh/year.
The solar resource in Malawi has been employed for various applications. Solar water heaters have been developed and are manufactured locally for domestic purposes. Total amount of installed solar water heaters in the country is estimated to have reached approximately 4 855 square meters. In addition, photovoltaic systems are also finding increasing use for various purposes such as lighting, water pumping, telecommunications repeater stations, refrigeration, and other appropriate applications. At present, there are more than10 000 photovoltaic systems installed in various parts of the country, with a total capacity of 165 kWp (CSR, 2005). There has been further growth, though small, in the SHS but no accurate figures are currently available. Six solar-wind hybrid systems have also been installed with Department of Energy Affairs support in Thyolo, Chiradzulu, Nkhata Bay, Mzimba, Nkhota-kota and Ntcheu (12 kW, each providing power for about 150 households). More recently, an 870 kWp solar photovoltaic plant has been commissioned at Lilongwe International Airport.
5.2.3 Wind energy
Wind energy has been used on a small scale to supply water for both livestock and irrigation in Malawi. Although there is a dearth of information on the wind energy characteristics of the country, it seems the wind speeds are moderate to low, typically in the range of 2.0 – 7.0 metres/second (GoM, 2003). Preliminary results from studies conducted by Malawi’s Meteorological Department suggest that the wind resource in Malawi cannot contribute significantly to a firm power generation; and that low speed aerogenerators could be operated for various applications such as milling of grains, pumping water and even lighting purposes in small remote villages around Malawi. It is particularly suited to water pumping as intermittent wind could still supply the needs when an adequate storage facility is incorporated. However, such assertion is contrasted by recent research findings which indicate that there is considerable potential for wind in the country. At present, the DoEA is collaborating with Malawi Renewable Energy Acceleration Programme (M-REAP) at the University of Malawi, an initiative funded by the Scottish Government, to undertake detailed wind measurements at five strategic sites as part of developing Malawi’s wind atlas.
5.2.4 Biomass and bio-energy
Biomass in the form of wood fuel is the largest form of primary energy consumed in Malawi, accounting for 97% of the total primary energy supply in the country (GoM, 2010b). Major sources of biomass available include fuel-wood and forestry residues, agricultural residues, animal dung, energy crops and municipal wastes. Forest reserves are the main sources of fuel-wood and contribute nearly 75% of the total biomass supply (Jumbe and Angelsen, 2011). Forests cover 3.2 million hectares, approximately 36% of the total land area with total available biomass resources being 275.5 million tonnes (Kambewa and Chiwaula, 2010). Sustainable fuel wood supplies from forests are estimated to be 42.4 million cubic metres of solid wood equivalent. Total demand for biomass energy is estimated at 8.92 million total wood equivalent or 13.38 million cubic metres solid wood.
Total bio-energy potential in Malawi is estimated between 0.1 and 0.5 EJ/year (Zyl et al, 2010). Crop residues have the biggest energy potential about 161 910 TJ/year, followed by forest residues (48 744 TJ). In addition, there are approximately 23 million animals (cattle, goats, sheep, pigs and chickens) and their manure can be used for the production of biogas (FAO, 2010). This number of animals gives a theoretical potential for biogas production of 1,387,195 m3 of biogas per day corresponding to 1100 GWhel/year of electricity or 914.5 GWhth/y of heat, assuming an average of 2.25 kWh/m3. This is about 74% of the electricity consumed in Malawi (electricity consumption amounted to 1478 GWh in 2012). In view of rising consumption, which is expected to quadruple over 2008 to 2030, using biogas to generate electricity could be a sensible way of improving electricity supply mix in Malawi.
Annual average production of sugarcane in Malawi is estimated at 2.5 million tons/year leaving behind over 950 000 tons baggase which is a significant power source. There are two sugar mills in Malawi having potential to generate 62 MWe of electricity but currently only 18 MWe has been utilised. Bagasse-based electrical generation estimated at 251GWh, corresponds to about 25% of national electricity generation (UNEP, 2013). The country can also explore biogas potential of municipal solid waste (MSW) as well. Current estimated municipal solid waste (MSW) generation per day is 720 tons which gives theoretical potential for biogas production of 32,683 m3/day corresponding to 70.6 MWhel/y or 58.8 MWhth/y (Karekezi et al., 2003).
Moreover, agricultural residues such as rice straw, sugarcane and cassava pulp have the potential to produce approximately 46.5 million litres ethanol production for the country. This could possibly displace over 40% of Malawi’s 2011 petrol consumption as transport fuel. Alternatively, the same amount of residue could provide 18.1 million litres per year of diesel to potentially offset 9.5% of natural diesel consumption in the transport sector. Presently, molasses-based ethanol amounting to 18 million litres/year, is being marketed as 10% blend with petrol. The total demand for ethanol is expected to be 33.6 million litres against present availability, resulting in scarcity of 15.6 million litres ethanol in the year 2015. Furthermore, bio-diesel produced from energy crops such as Jatropha curcas, soya beans, cotton, sunflower and groundnuts has the potential to produce 50 million litres of bio-diesel, equivalent to 583, 530 TJ/year of energy.
5.2.5 Geothermal energy
Geothermal energy has been extensively used for power generation and direct power applications in many countries of the world (Fridleifsson, 2003). As a consequence of Malawi’s location in the East African Rift System (EARS), the country is endowed with significant potential reserves of geothermal energy. There are approximately 55 geothermal spots in Malawi, but three major ones identified for detailed investigation are: Chiweta, Mwankeja, and Nkhotakota. The combined geothermal potential from these major areas is 200 MWe (Gondwe et al., 2012). As for geothermal projects, some studies have been conducted to design a prototype Geothermal Power Plant for producing electricity. One of the ongoing related projects is a 30 MW Geothermal Power Plant at exploring stage in Nkhotakota, to be upgraded to 100 MW depending on the results of exploration drilling.